1. Field of the Invention
The present invention relates to a structure for mounting an automotive battery and, more particularly, to a structure for mounting an automotive battery in a rear part of a vehicle body.
2. Description of the Related Art
In an automobile such as a compact car, a space in an engine room formed at a front part of a vehicle is usually small. Therefore, in the case of storing a gasoline engine, an electric motor, and accessories of the both in the engine room in order to form such a small car into a hybrid car, a battery as an automotive power source, which is generally disposed in the engine room, is removed to a rear part of the vehicle such as a trunk room thereof. Thereby, a larger space is made in the engine room, so that the degree of freedom for a vehicle design can be increased.
Similarly, even in an electric car based on a conventional vehicle with a gasoline engine mounted thereon, it is convenient to dispose the battery as an automotive power source into the rear part of the vehicle, so that the same effect as mentioned above is obtained. Moreover, a large-sized battery for supplying electric power to the electric motor is mounted at a lower part of the vehicle, separately from the battery as an automotive power source.
Furthermore, in a front-engine, front-drive type vehicle, there is an example of similarly disposing the battery in the rear part of the vehicle in order to prevent the weight of the vehicle front part from increasing as disclosed in Japanese Utility Model Publication No. 3058/1988.
As mentioned above, if the battery is mounted at the rear part of the vehicle, the larger space is obtained in the engine room, so that the degree of the freedom for arranging the components in the engine room is increased, and also the degree of freedom for designing the whole vehicle is expanded. In addition, a maneuverability of the vehicle can be increased since the weight of the vehicle front part is prevented from increasing. Furthermore, since the battery and components for mounting the same are not disposed at the front part of the vehicle, the rigidity of the vehicle front part is prevented to locally increase. Thereby, when an impact load over a predetermined value is applied from a front direction of the vehicle to the vehicle itself, a proper crash stroke is obtained, so that a safety can be increased.
However, when the impact load over the predetermined value is applied from a rear direction of the vehicle, a deformation of the vehicle rear part may occur, so that there is likelihood that the battery may break or an electrolyte thereof may leak from the broken battery.
Accordingly, an object of the invention which has been made in the light of the foregoing is to provide a structure for installing an automotive battery which would protect the battery installed in a rear part of a vehicle body. The present invention contains the following features which are considered improvements over the prior art.
(1) In a structure for installing an automotive battery in which the battery is mounted on a battery mounting base provided on a floor in a rear part of a vehicle body, a rear suspension cross member extends along the direction of vehicle width beneath the floor, and the battery mounting base is located within an area of the floor corresponding to the location of the rear suspension cross member in plan view.
Generally, the rear suspension cross member is essential in a rear suspension structure and is used for connecting a lateral link of the rear suspension to a vehicle body frame while sustaining mainly horizontal stress and reaction force produced from the road surface or rear suspension during driving. For example, since the rear suspension cross member supports link components which constitute the rear suspension in a front-wheel-drive vehicle, and the rear suspension cross member also retains a differential gear at the same time in a four-wheel-drive vehicle, the rear suspension cross member itself is large-sized and has an extremely high stiffness.
Thus, according to a first aspect of the invention, the area of the floor overlapping with the rear suspension cross member is reinforced by the strong rear suspension cross member and the battery mounting base is installed in the reinforced area of the floor, so that where its rigidity has been ensured, so that deformation of the area of the floor where the battery mounting base for supporting the battery is provided is prevented or significantly reduced even when the rear part of the vehicle body deforms due to an impact load of a specific value or above applied to the vehicle body from behind. As a consequence, deformation of the battery mounting base is prevented and breakage of the battery is avoided.
Furthermore, since the aforementioned area of the floor is strengthened by the existing rear suspension cross member, there is no need for additional stiffening members and it is possible to avoid weight increase and suppress an increase in production cost.
(2) In the invention as recited in section (1), the battery mounting base comprises a battery mounting surface on which the battery is mounted, a front surface part extending downward from a front edge of the battery mounting surface with a lower end of the front surface part connected to the floor, and a rear surface part extending downward from a rear edge of the battery mounting surface with a lower end of the rear surface part connected to the floor.
According to the invention of this section (2), the battery mounting base is formed of a simple structure including the battery mounting surface on which the battery is mounted, and the front surface part and the rear surface part extending downward from the front and rear edges of the battery mounting surface, respectively.
(3) In the invention as recited in section (2), the front surface part has a first physically weak portion formed in the front surface part.
According to the invention of this section (3), the first physically weak portion is formed in the front surface part of the battery mounting base. Therefore, when members of the vehicle body, such as a rear skirt, come into contact with the battery due to an impact load exerted from behind the vehicle body, the first physically weak portion formed in the front surface part collapses and deforms, causing the battery to topple toward the front of the vehicle body. As a consequence, the impact is alleviated and breakage of the battery is avoided or significantly reduced.
(4) In the invention as recited in section (3), there is provided a second physically weak portion in an area of the battery mounting surface on the rear of its center in the longitudinal direction of the vehicle body.
According to the invention of this section (4), there is provided the second physically weak portion in a rear part of the battery mounting surface in addition to the first physically weak portion of section (3) of the invention. Therefore, when members of the vehicle body, such as the rear skirt, come into contact with the battery, not only the first physically weak portion but also the second physically weak portion deforms so that the rear part of the battery mounting surface is lifted upward and the battery is caused to topple frontward in a more reliable fashion. As a consequence, the impact exerted on the battery is more alleviated and breakage of the battery is prevented or reduced more positively.
(5) In the invention as recited in section (2) or (4), the rear surface part extends obliquely upward toward the front of the vehicle body.
According to the invention of this section (5), when a turning force is exerted on the rear suspension cross member forcing its front portion upward due to an impact load applied from behind the vehicle body, the rear edge of the battery mounting surface is supported by the inclined rear surface part the first physically weak portion collapses and deforms due to the impact. Consequently, the battery mounted on the battery mounting surface is kept from turning over rearward and held in a stable position, so that its breakage is prevented or reduced.
(6) In a structure for installing an automotive battery in which the battery is mounted on a battery mounting base provided on a floor in a rear part of a vehicle body according to a second aspect of the invention, a rear suspension cross member extends along the direction of vehicle width beneath the floor, and the battery mounting base includes a battery mounting surface on which the battery is mounted, a front surface part extending downward from a front edge of the battery mounting surface and connected to the floor in its area corresponding to the location of the rear suspension cross member in plan view, a rear surface part extending downward from a rear edge of the battery mounting surface with a lower end of the rear surface part connected to the floor at the rear of the rear suspension cross member in plan view, and a first physically weak portion formed in the front surface part.
According to the invention of this section (6), when a rear part of the vehicle body deforms due to an impact load applied to the vehicle body from behind, a rear part of the battery mounting surface is forced upward by the rear surface part whose lower end is connected to the floor which deforms and is pushed frontward. At the same time, the first physically weak portion formed in the front surface part deforms and the battery mounting surface inclines, causing the battery to list frontward. As a consequence, the battery is kept from going into contact with members of the vehicle body, such as a rear skirt, or impact force due to their contact is alleviated, so that breakage of the battery is prevented or significantly reduced.
(7) In the invention as recited in sections (1) to (6), the structure comprises a mounting base plate provided on the battery mounting surface for mounting the battery, the mounting base plate provided on the battery mounting surface has a bottom surface whose width is larger than the width of the battery mounting surface measured in the longitudinal direction of the vehicle body.
According to the invention of this section (7), it is possible to install a battery having a larger width than the width of the battery mounting surface measured in the longitudinal direction.
(8) In the invention as recited in sections (1) to (6), the structure comprises a mounting base plate provided on the battery mounting surface, the mounting base plate having a bottom portion on which the battery is mounted and a surrounding wall which extends upward from the periphery of the bottom portion and surrounds the outer periphery of the battery.
According to the invention of this section (8), the battery is protected against an impact load or the like by the mounting base plate, especially by the surrounding wall. Furthermore, even when the battery is broken, dispersion of its fragments and electrolyte is avoided by the surrounding wall and the electrolyte is kept from flowing out by the box-shaped mounting base plate including an electrolyte storage.
(9) In the invention as recited in section (8), the surrounding wall has an electrolyte storage formed by making an outward swelling on the surrounding wall.
According to the invention of this section (9), the electrolyte is kept from flowing out more securely than the above feature (8) since the electrolyte storage is formed by making an outward swelling on the surrounding wall.